1. Field of the Invention
The present invention relates to a method of and an apparatus for inspecting a wire end whose coating is stripped to expose its core, and more particularly, it relates to a method of and an apparatus for inspecting a stripped wire end, employed in an automatic terminal application apparatus.
2. Description of the Prior Art
In an automatic terminal application apparatus for continuously and automatically performing terminal application processing including a process of stripping the coating of a wire end and a process of applying a terminal to the stripped portion by pressure, generally performed is inspection through a as shown in FIG. 1, for example, which is disclosed in Japanese Utility Model Laying-Open Gazette No. 153089/1981 in the name of Shin Meiwa Industry Co., Ltd., the assignee of this case, in order to inspect whether or not the coating stripping process is effectively performed. The detecting brush is formed by a pair of plate spring electrodes 1 and 2, which are provided on a processing path (transfer path for a wire end) of an automatic terminal application apparatus so that an exposed core portion 3 of a wire whose coating is stripped passes through the same.
The plate spring electrodes 1 and 2 are generally separated from each other with a small space to be in nonconducting states as shown in FIG. 1, for example. When the plate spring electrodes 1 and 2 are further separated from each other by the core portion 3 passing through the said space, a decision of effective stripping is made upon conduction while a decision of defective stripping is made on the assumption that the core is not exposed if the electrodes 1 and 2 remain in the nonconducting states. The plate spring electrodes 1 and 2 may be partially in contact with each other to be normally retained in conducting states, and in this case, a decision of effective stripping is made if the electrodes 1 and 2 remain in the conducting states when the core portion 3 separates the electrodes 1 and 2 from each other to pass through the contact portion, while a decision of defective stripping is made if the electrodes 1 and 2 enter nonconducting states.
In a conventional inspection method employing such a detecting brush, fine adjustment must be performed in response to the diameter of the wire and the spring constant (pressing force) of the plate spring electrodes in order to avoid erroneous inspection and defective application in the subsequent terminal application process, which fine adjustment is troublesome while operation stability of the automatic terminal application apparatus is influenced by the degree of the fine adjustment. For example, when the pressing force between the plate spring electrodes 1 and 2 is decreased with respect to a large-diametrical wire having a hard core, the exposed core portion 3 may push up only one of the plate spring electrodes (e.g., the electrode 1) to pass through the space between the same, thereby to cause erroneous inspection. If the pressing force between the plate spring electrodes 1 and 2 is strong as compared with the hardness of the core to the contrary, the core is inevitably bent when the exposed core portion 3 passes through the space between the plate spring electrodes 1 and 2, to cause erroneous application of the terminal in the subsequent process.